Why some people say that Lsb Matching requiring the original cover although it will be removed the fist lsb and reside removed bits from every byte to form secret message, my opinion we dont need it because we shall take every byte sequentially and drag fist bit regardless of if we add or subtract one to pixel value and we dont care of get back the cover as it was ????,
The second question:
what is the meaning between Data distributed uniformly or randomely when we are applying steganography method?
what is Luminance that its formula:
Luminance L = (0.299 x Red) + (0.587 x Green) + (0.114 x Blue
what is relation to pixel properties?

please if you can'y help me tell me about specialized persons in data hiding to deal with them

well for a start that luminance Luminance - Wikipedia, the free encyclopedia as you call it I just call RGB and basically it tells your computer the proportions of red green and blue light to mix in order to get the color you want your pixel to be. Might take a look at the rest later
This might help though HOW TO HIDE FILES IN A JPG
Set up:1. Must have a .zip or .rar compressor.
2. Willingness to learn.
Steps:
1. Save the picture of choice to your desktop.
2. Make a new .rar or .zip folder on your desktop.
3. Add the files you want to hide into the .zip or .rar
4. Click start menu, run, cmd.
5. In Command Prompt type cd "desktop" with the quotation marks.
6. Now type in copy /b picturename.jpg + foldername.rar outputfilename.jpg
( If you use .zip then: copy /b picturename.jpg + foldername.zip outputfilename.jpg)
7. Now there should be the outputed file name with a .jpg extension on the desktop.
( Do not close Command Prompt just yet )
8. Double click it to open the picture and check it out.
9. When your done looking, and want to view the hidden files
Type: ren outputfilename.jpg outputfilename.rar or zip
Now you're done!
A quick info-fact:
With this technique of hiding files in a jpg you can send this to anyone and they just
have to rename the file extension to .zip or .rar.
With this technique the Al-Qaeda operatives were able to send info to others
secretively.Secondly lsb matching requires the original image to act like a key. The differences between the two images will be the pixels that have been encrypted without the original image it is practically impossible to decrypt it. Uniformally or randomally basically means the spaces between the pixels that the image is coded in basically this can be set say evey 40pixels there is a line of code a letter or whatever and so on. Or these pixels could be distributer randomally ie following a certain function so it could go something like info after 30px then 22px then 66px etc. Generally random is harder to decrypt.

Untitled.jpg
in above picture and after applying decryption function they draw that we have media object and hidden information ,why??
we don't need to repair distorted cover in the deccrytion step just we need to retrieve our secret data from it so what is the meaning that they draw two objects (media,secret data)??? as I know extracting step just needs stego image and the output is hidden data from it what represent the media word reffered to by red arrow in the above picture ??? Does it represent residual image after removing hidden data??

yeah but if you look at both images closely you will realise that they sent another picture and a audio file in the original image as well as a text file containing the secret data. The media being the pic and audio file. This sounds like homework by the way.http://en.wikipedia.org/wiki/Steganography see there is an image of a cat in the image of the tree